In the current “Upper Layer (Layer 3) Signalling Standard for CDMA2000 Spread Spectrum Systems, Release 0” (3GPP2 CS0005-0 Version 3.0), section 2.6.5.1.3, the contents of which are incorporated herein by reference, specifies that a mobile station must increment a timer-based registration counter once every 80 ms whenever a variable entitled COUNTER_ENABLED is set to YES. If the mobile station is operating in slotted mode, it can increment the timer-based registration counter when it begins to monitor the Paging Channel and it should increment its counter as if it was in non-slotted mode.
The same standard requires that the registration period be calculated with the formula T=2PRD/4×80 ms where PRD is in the range of 29 to 85. At the longest period for re-registration, the above standard therefore requires that a mobile station needs more than 2.4 million interrupts before the mobile performs a registration. At the shortest time period the number of interrupts required is 152.
When a mobile enters a slotted mode, the mobile is supposed to be relieved from the above burden since there should be no interrupts during the sleep period because the CPU is shut down. However, in reality, this is still unworkable. Many mobile devices include PDA and game functionality and thus the CPU is still busy while the CDMA is sleeping. The number of interrupts affects both the battery life and performance of the CPU and a solution is therefore required that would reduce the number of interrupts on the CPU.